A dermal delivery device is an adhesive “patch” for application to the skin that is used to deliver a wide variety of pharmacologically and cosmetically active agents. Such patches can be used to deliver an agent transdermally, i.e., through the skin and into the bloodstream for systemic treatment or into or through the skin for local treatment. Such patches can also be used to administer topical treatments, including cosmetically active agents.
Transdermal drug delivery devices intended for extended wear, i.e., 3 or more days, are susceptible to problems of inadequate adhesion and/or skin irritation. Irritation can be caused or exacerbated by a number of factors, including the nature of the active. Certain skin permeation enhancers are also known to contribute to irritation. These include dimethyl sulfoxide (DMSO) and long chain aliphatic compounds including fatty acids, such as laurates and oleates and derivatives thereof, e.g., lauryl alcohol.
Various attempts have been made to address the skin irritation problem. These include controlling the rate of transdermal delivery of irritating drugs through use of a rate controlling membrane, inclusion of irritation inhibitors such as a lysozymal uptake inhibitor, a complexing agent, a second active agent that reduces irritation/sensitization, a sucrose fatty acid, aluminum hydroxide and/or titanium oxide. In some cases, a particular salt of an irritating active may be found to be less irritating.